A medical electrical lead typically includes one or more elongate conductors, each of which electrically couples an electrode of the lead to a corresponding connector contact of the lead. A conductive coupling between a lead conductor and electrode should add a minimum of electrical resistance to the electrical circuit, which is formed by the electrode, conductor, and contact, and should have an adequate strength to maintain good contact under operational loading conditions.
Because medical electrical leads are typically constructed to have the lowest possible profile, without compromising functional integrity, reliability and durability, relatively low profile conductive couplings, which do not significantly increase a profile of the lead are also desired. Although some low profile conductive couplings have been previously disclosed, there is still a need for improved couplings which, in addition meeting the above criteria, provide flexibility in the manufacture of various configurations of medical electrical leads.
As lead bodies become smaller and the height of the connections between conductors and electrodes is reduced, it becomes increasing difficult to make low profile junctions that allow conductor coils to be welded to without damaging or significantly affecting the cable. For example, a radially symetrical crimp barrel or crimp sleeve located entirely within a lead lumen as described in U.S. patent application Ser. No. 11/549,284 filed Oct. 13, 2006, now abandoned, may only have a 3 mil wall due to height constraints. The thermal mass, wall thickness and available material to make an effective weld is negligible. Prior designs such as those disclosed in U.S. Pat. No. 5,676,694 issued to Boser et al and incorporated herein by reference in its entirety have provided an extension to the crimp sleeve which extends outward from the lead lumen to the exterior of the lead body, allowing the a weld to an associated electrode coil to be made spaced from the lead conductor. However, further reductions in lead profile are still desirable over leads fabricated using this connector mechanism.